The total value of derivatives in the world exceeds total global gross domestic product by a factor of 10, said Mobius, who oversees more than $50 billion. With that volume of bets in different directions, volatility and equity market crises will occur, he said.The global financial crisis three years ago was caused in part by the proliferation of derivative products tied to U.S. home loans that ceased performing, triggering hundreds of billions of dollars in writedowns and leading to the collapse of Lehman Brothers Holdings Inc. in September 2008.